ANALYSIS OF SWITCHING TRANSIENTS OF A DEENERGIZED CIRCUIT IN A DOUBLE-CIRCUIT TRANSMISSION-LINE

Determination of the capacity of the earthing switch for the de-energized line used in a substation requires a precise analysis of the transient induction voltage and current during a switching operation caused by the nearby live line. This paper shows that the line conductor height has the strongest effect on the steady-state induced voltage of the de-energized line of a double-circuit transmission line, and that geometrical factors should be taken into consideration carefully for long distance lines installed in mountainous areas. As for the transient current and voltage following the switching operation, the analytical results show that the timing of the switching operation is a key factor determining the maximum transient current experienced by the earthing switches and the maximum transient voltage attained is twice the steady-state induced voltage. The inclusion of line parameter frequency dependence decreases the crest value of the transient voltage and decreases its attenuation time constant. © 1990.